A multi-layered circuit board is produced by stacking insulating layers on surfaces of which wiring patterns are formed with copper foils or other materials. When the multi-layered circuit board is used as a mounting board for mounting electronic components thereon such as semiconductor chips, a capacitor that functions as a bypass capacitor may be included in the multi-layered circuit board. An equivalent series inductance (ESL) of such a capacitor increases proportional to a length of wiring between the capacitor and the electronic component. As a result, high-frequency characteristics of the multi-layered circuit board degrade. A technology to resolve such a problem by enclosing the capacitor between insulating layers and arranging the capacitor adjacent to the electronic component has been known.